黄龙病菌感染对长春花 SOD 和 POD 活性的影响

【目的】比较黄龙病菌感染对长春花叶、茎、根 3 个组织中超氧化物岐化酶（SOD）和过氧化物酶（POD） 活性的影响。【方法】采用分光光度计法测定黄龙病菌感染后长春花叶、茎、根 3 个组织中 SOD 和 POD 的活性。 【结果】染病长春花中 SOD 活性随感染时间的增加,逐渐下降,活性最低时,叶、茎和根 SOD 活性分别只有健 康对照的 61%、55% 和 47%。3 个组织间 SOD 活性总体表现为叶 > 茎 > 根。染病长春花中 POD 活性随感染时间 的增加呈现先上升后下降的趋势,叶、茎和根 POD 活性最高出现在嫁接后 30、35、35 d,活性分别为健康对照 的 205%、254% 和 194%,根中 POD 活性总体较叶、茎部高。【结论】黄龙病菌感染对长春花各组织中 SOD 和 POD 酶的活性均有较大影响,SOD 和 POD 活性的增加对长春花抵抗 CaLas 侵染起重要作用。     

亚洲韧皮杆菌在单株脐橙病树的分布情况

【目的】研究亚洲韧皮杆菌(CLas)在纽荷尔脐橙病树的分布情况,为柑橘黄龙病(HLB)的防控提供参考依据。【方法】以1~3个枝条表现斑驳黄化叶片症状的纽荷尔脐橙病树为研究对象,对主干发出的5个主枝(A、B、C为斑驳黄化枝条,D、E为无症状枝条)的叶片分别取样,运用PCR和实时荧光定量PCR(qPCR)分别检测,用2-ΔΔCt法分析树体各部分黄龙病菌含量。对于果树上表现典型HLB病果但叶片无症状的结果枝,分别检测典型病果和相应叶片的感病情况。【结果】PCR对A、B、C、D、E的阳性检出率分别为88.57%、61.11%、54.17%、6.67%和0,qPCR对A、B、C的阳性检出率均为100.00%,对D、E的阳性检出率分别为40.00%和13.33%;2-ΔΔCt法分析发现,斑驳黄化叶片中病原菌含量更高,病果的阳性检出率高于相应的无症状叶片样品。【结论】CLas在表现典型斑驳黄化症状的叶片和果实中的含量及阳性检出率均较高,病原菌在病树中分布不均匀。在进行HLB检测时,应选取典型或疑似症状样品,并运用qPCR进行检测,一旦发现树体局部发病,应当整株销毁。     

Field effect of Cnaphalocrocis medinalis granulovirus (CnmeGV) on the pest of rice leaffolder

Rice leaffolder, Cnaphalocrocis medinalis(Guenée), has become a major pest throughout the rice cultivating areas of China and caused severe damage to rice production. Cnaphalocrocis medinalis granulovirus(CnmeGV), a naturally occurring baculovirus, is revealed as a potential microbial agent for the pest control. Field applications of CnmeGV were conducted against rice leaffolder larvae in rice paddies. CnmeGV infected the larvae not only in the current generation but also in the successive generation, resulting in a sustained infection in the larva population for at least 48 days. Under diferent concentrations of CnmeGV(7.5×10~(11) and 1.125×10~(12) occlusion body(OB) ha~(-1)) at 30 days after spraying, larval population reduced up to 76.32% and rice leaf rolled rate kept in 15.42%. Simultaneously, CnmeGV had no impact on arthropod predators of C. medinalis, with abundances ranging from 2.39 to 3.79 per ten hills. These results revealed that CnmeGV is suitable as a bio-pesticide for rice leaffolder management in rice paddies.     

Sublethal effects of sulfoxaflor on the fitness of two species of wheat aphids,Sitobion avenae(F.) and Rhopalosiphum padi(L.)

Sitobion avenae(F.) and Rhopalosiphum padi(L.) are two important pests of wheat in China. They typically coexist in fields during the late period of wheat growth. Sulfoxaflor is a novel sulfoximine insecticide that demonstrates broad-spectrum efficacy, especially in targeting sap-feeding insects. This study was carried out to investigate the sublethal effects of sulfoxaflor on the development, longevity, and reproduction of two species of wheat aphids. Our results showed that sublethal concentrations of sulfoxaflor did not cause significant effects on the fecundity or the longevity of the parent generation(F_0 generation) of either S. avenae or R. padi. However, it caused transgenerational sublethal effects. For S. avenae, adult longevity of F_1 generation was significantly decreased. No significant differences were observed on the population parameters of S. avenae in the F_1 generation. For R. padi, the adult preoviposition period(APOP) and the total preoviposition period(TPOP) of F_1 generation were significantly reduced. The mean generation time(T) was significantly reduced in the R. padi F_1 generation. What's more, the intrinsic rate of increase(r_m) and the finite rate of increase(λ) were significantly increased in the R. padi F_1 generation. Taken together, these results suggest that exposure to the LC_(25) of sulfoxafl had no effects on the parent generation of S. avenae or R. padi, but it reduced adult longevity of S. avenae as a negative effect and increased the r_m and λ of R. padi in the first progeny generation, which may have an impact on the population dynamics of R. padi.     

浙江省亚洲柑橘木虱黄龙病病原分布与消长规律

亚洲柑橘木虱Diaphorina citri Kuwayama是黄龙病病原Candidatus Liberibacter asiaticus(CLas)的主要传播媒介.为更好地探清亚洲柑橘木虱上的CLas阳性分布特性及其动态变化,提出适宜治虫防病的窗口期,特针对浙江省柑橘果园的分布特点,于2002—2019年采取定园定...     

Alanine-substituted mutant on Gly~(373) and Asn~(375) of Cry1Ai-h-loop 2 causes reduction in both toxicity and binding against Helicoverpa armigera

Cry1Ai-h-loop 2 is a mutant of Cry1Ai constructed by exchanging loop 2 from Cry1Ah protein and shows insecticidal activity against Helicoverpa armigera. The toxicity of Cry1 Ai-h-loop 2, in contrast to the very low toxicity of Cry1Ai, is closely associated with the eleven residues in the loop 2 region. To characterize the key sites of loop 2 in Cry1Ai-h-loop 2, alaninesubstituted mutants were generated. The toxicity of these mutants against H. armigera indicated that dual-mutant on Gly373 and Asn375 caused a significant decrease in toxic activity. ELISA binding and competition binding assays demonstrated that the reduction of toxicity in the mutant of interest was correlated with decreased binding affinity.     

Comparison of phenolic profiles and antioxidant activities in skins and pulps of eleven grape cultivars(Vitis vinifera L.)

Eleven grape cultivars were analysed to explore the variety differences of fresh grape phenolic profiles. The results showed that free phenolics were predominant in grape skins and pulps, and showed the higher antioxidant activities than bound. In 11 cultivars, Muscat Kyoho extracts had the highest total phenolic content in skins(10.525 mg GAE g~(–1) FW) and pulps(1.134 mg GAE g~(–1) FW), and exhibited the highest DPPH radical scavening capacity(EC_(50)=11.7 μg mL~(–1)) and oxygen radical absorbance capacity(ORAC) value(190.57 μmol TE g~(–1) FW) of free phenolic in skin. In addition, the most abundant phenolics in grape skins were found to be flavonoids such as kaempferol in Kyoho skin(541.2 μg g~(–1) FW), rutin, catechin and epicatechin in Muscat Kyoho skin(262.3, 86.3 and 70.0 μg g~(–1) FW, respectively). Furthermore, the principal component analysis showed a strong difference of phenolic profiles with the cultivars, existing forms and distributions. Pearson correlation coefficient analysis showed a significant linear correlation between total phenolic content and antioxidant activity(P0.05). Therefore, both skins and pulps were rich sources of bioactive phenolic compounds, and Muscat Kyoho was the ideal source among all samples.     

Crosstalk of cold and gibberellin effects on bolting and flowering in flowering Chinese cabbage

The flower stalk is the product organ of flowering Chinese cabbage(Brassica campestris L.ssp.chinensis var.utilis Tsen et Lee),which is cultivated extensively in South China.Flower stalk formation and development,including bolting and flowering,determine the yield of flowering Chinese cabbage;however,the bolting and flowering mechanisms remain to be explored.To elucidate these processes,we studied the effects of low-temperature and gibberellin(GA)treatments,and their interaction,on stem elongation,bolting time,flowering time,hormone content,and cell morphology in stem of flowering Chinese cabbage.The results showed that both cold and GA treatments accelerated bolting time,stem elongation,and flowering time.Moreover,cold and GA cotreated plants displayed additive positive effects.In addition,cold treatments increased the GA,indole-3-acetic acid,and cytokinin contents and altered cell size in the shoot apices of flowering Chinese cabbage.Treatment with uniconazole,a GA synthesis inhibitor,strongly delayed bolting time,stem elongation,and flowering time,whereas GA,but not cold treatment,rescued this inhibition,indicating that low temperature accelerates bolting and flowering not only through inducing GA in the shoot apices,but also other ways.These results provide a theoretical basis for further dissecting the regulatory mechanism of bolting and flowering in flowering Chinese cabbage.     

Molecular identification and enzymatic properties of laccase2 from the diamondback moth Plutella xylostella (Lepidoptera: Plutellidae)

Laccase(EC 1.10.3.2)is known to oxidize various aromatic and nonaromatic compounds via a radical-catalyzed reaction,which generally includes two types of laccase,Lac1 and Lac2.Lac1 oxidizes toxic compounds in the diet,and Lac2 is known to play an important role in melanizing the insect exoskeleton.In this study,we cloned and sequenced the cDNA of the diamondback moth,Plutella xylostella Lac2(PxLac2),from the third instar larvae using polymerase chain reaction(PCR)and rapid amplification of cDNA ends techniques.The results showed that the full-length PxLac2 cDNA was 1 944 bp long and had an open reading frame of 1 794 bp.PxLac2 encoded a protein with 597 amino acids and had a molecular weight of 66.09 kDa.Moreover,we determined the expression levels of PxLac2 in different stages by quantitative PCR(qPCR).The results indicated that PxLac2 was expressed differently in different stages.We observed the highest expression level in pupae and the lowest expression level in fourth instar larvae.We also investigated the enzymatic properties of laccase,which had optimal activity at pH 3.0 and at 35°C.Under these optimal conditions,laccase had a Michaelis constant(K_m)of 0.97 mmol L~(-1),maximal reaction speed(V_m)of 56.82 U mL~(-1),and activation energy(E_a)of 17.36 kJ mol~(-1) to oxidize2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid ammonium salt).Type II copper enhanced laccase activity below 0.8mmol L~(-1) and reduced enzyme activity above 0.8 mmol L~(-1) with an IC_(50) concentration of 1.26 mmol L~(-1).This study provides insights into the biological function of laccase.     

First report of cereal cyst nematode (Heterodera filipjevi) on winter wheat in Shandong Province,China

正The cereal cyst nematodes(Heterodera avenae,Heterodera filipjevi,Heterodera latipons)are considered to be one of the most important plant parasitic nematodes attacking most cereals and can cause significant crop losses(Sikora 1988).In China,H.filipjevi(Madzhidov 1981)Stelter,1984,was first reported from Henan province(peng et al.2010)and a few years later in Anhui province and Xinjiang Uygur Autonomous Region(peng et al.2016,2018).In December 2017,a survey for cereal     

First detection and complete genome of Soybean chlorotic mottle virus naturally infecting soybean in China by deep sequencing

Soybean chlorotic mottle virus (SbCMV) was first detected from soybean plants in Jiangxi Province of China by high throughput sequencing and was confirmed by PCR. The complete nucleotide sequence of NC113 was determined to be 8 210 nucleotides, and shared the highest similarity (91.7%) with sequences of SbCMV that was only reported in Japan. It encodes nine putative open reading frames (ORFs Ia, Ib and II–VIII), and contains a large intergenic region located at nucleotide 5 976–6 512 between ORFs VI and VII. Sequence analysis and phylogenetic tree indicated that NC113 is an isolate of SbCMV, and is more related to the soymoviruses Blueberry red ringspot virus (BRRSV), Peanut chlorotic streak virus (PCSV) and Cestrum yellow leaf curling virus (CmYLCV) than to other representative members in the Caulimoviridae family. Field survey of 472 legume plants from Jiangxi and Zhejiang provinces showed SbCMV was only detected from soybean in Nanchang City with a low incidence rate. This is the first report of Soybean chlorotic mottle virus identified in China.     

A rapid,simple, and sensitive immunoagglutination assay with silica nanoparticles for serotype identification of Pseudomonas aeruginosa

An agglutination test based on colored silica nanoparticles (colored SiNps) was established to detect serotypes of Pseudomonas aeruginosa. Monodisperse colored SiNps were used as agglutination test carriers. The colored SiNps were prepared through reverse microemulsion with reactive dyes, sensitized with 11 kinds of mono-specific antibodies against P. aeruginosa, and denoted as IgG-colored SiNps. Eleven kinds of IgG-colored SiNps were individually mixed with P. aeruginosa on a glass slide. Different serotypes of P. aeruginosa could be identified by agglutination test with evident agglutination. The P. aeruginosa could be detected in a range from 3.6 × 10⁵ to 3.6 × 10¹² cfu mL^?1. This new agglutination test was confirmed to be a specific, sensitive, fast, easy-to-perform, and cost-efficient tool for the routine diagnosis of P. aeruginosa.     

GsMAPK4, a positive regulator of soybean tolerance to salinity stress

Salt stress is one of the major factors affecting plant growth and yield in soybean under saline soil condition. Despite many studies on salinity tolerance of soybean during the past few decades, the detailed signaling pathways and the signaling molecules for salinity tolerance regulation have not been clarified. In this study, a proteomic technology based on two-dimensional gel electrophoresis (2-DE) and mass spectrometry (MS) were used to identify proteins responsible for salinity tolerance in soybean plant. Real-time quantitative PCR (qRT-PCR) and Western blotting (WB) were used to verify the results of 2-DE/MS. Based on the results of 2-DE and MS, we selected glucosyltransferase (GsGT4), 4-coumarate, coenzyme A ligase (Gs4CL1), mitogen-activated protein kinase 4 (GsMAPK4), dehydration responsive element binding protein (GsDREB1), and soybean cold-regulated gene (GsSRC1) in the salinity tolerant soybean variety, and GsMAPK4 for subsequent research. We transformed soybean plants with mitogen-activated-protein kinase 4 (GsMAPK4) and screened the resulting transgenics soybean plants using PCR and WB, which confirmed the expression of GsMAPK4 in transgenic soybean. GsMAPK4-overexpressed transgenic plants showed significantly increased tolerance to salt stress, suggesting that GsMAPK4 played a pivotal role in salinity tolerance. Our research will provide new insights for better understanding the salinity tolerance regulation at molecular level.     

Effect of exogenous GA_3 on flowering quality,endogenous hormones,and hormone-and flowering-associated gene expression in forcing-cultured tree peony(Paeonia suffruticosa)

Gibberellins(GAs) promote flowering in the forcing-cultured tree peony(Paeonia suffruticosa), however, the mechanism of regulating flowering is not fully understood. In this study, exogenous GA_3 was applied to five-year-old Luoyang Hong plants to explore responses in terms of endogenous hormones, flowering quality, and the hormone-and flowering-associated gene expression. Exogenous GA_3 application significantly promoted flower bud development and new branch growth, as well as improved flowering quality. Exogenous GA_3 application also stimulated the synthesis of endogenous GA_3 and indole-3-acetic acid(IAA) but reduced abscisic acid(ABA) levels. To further elucidate the regulatory mechanism, eight genes for GA biosynthesis and signaling, including Ps CPS, Ps KS, Ps GA_3 ox, Ps GA2 ox, Ps GID1 b, Ps GID1 c, Ps DELLA, and Ps GID2 were cloned for the first time, and sequence analysis was also performed. The results suggested that all the cloned genes have conserved structure as each homologous gene reported in the other species. Phylogenetic trees constructed by the each cloned gene showed that the phylogenetic evolutionary relationship of P. suffruticosa was closely related to Vitis vinifera. The expression patterns of the above genes, and genes for ABA and IAA biosynthetic and signaling, and the flowering time were also investigated. Most of the above genes showed higher expression in the control buds than those in the GA_3 treated buds at six developmental stages, whereas the expression levels of PsSOC1 and PsSPL9 were up-regulated by GA_3 treatment. The results also showed that the GA-biosynthetic and signaling pathways are conserved in tree peony, and the PsCPS, PsGA_3 ox, PsGA2 ox, PsGID1, PsDELLA, and PsGID2 genes are necessary for feedback regulation of GAs. Furthermore, hormone changes promoted PsSOC1 and PsSPL9 expression, and repressed PsSVP expression, which contributed to the improvement flowering quality in tree peony of forcing culture.     

Molecular,serological and biological characterization of a novel Apple stem pitting virus strain from a local pear variety grown in China

Apple stem pitting virus (ASPV) is an important causal agent of pear diseases. Nowadays, the infection status and molecular characteristics of the virus in old pear trees have never been investigated. In this study, we provide the first complete genome sequence of an ASPV isolate LYC from an over 300-year-old tree of a local Pyrus bretschneideri cultivar ‘Chili’ specifically grown at Laiyang area in China. ASPV-LYC possesses a chimeric genome consisting of 9 273 nucleotides excluding a poly(A) tail at its 3’ end and harboring a recombination region in its open reading frame (ORF1) with Aurora-1 and KL9 identified as the major and minor parents. Western blot analysis with antisera against recombinant coat proteins (CPs) of three ASPV isolates from pear indicates that ASPV-LYC is serologically related to these ASPV isolates, but with differential activities. Further biological tests on indicator plants of Pyronia veitchii show that ASPV-LYC can induce serious leaf and stem symptoms as other ASPV isolates. The results provide an important information for understanding molecular evolution of ASPV and suggest a need to prevent dissemination of the isolate among pear trees.     

The synergistic advantage of combining chloropicrin or dazomet with fosthiazate nematicide to control root-knot nematode in cucumber production

The highly-damaging root-knot nematode(Meloidogyne spp., RKN) cannot be reliably controlled using only a nematicide such as fosthiazate because of increasing pest resistance. In laboratory and greenhouse trials, we showed that chloropicrin(CP) or dazomet(DZ) synergized the efficacy of fosthiazate against RKN. The combination significantly extended the degradation half-life of fosthiazate by an average of about 1.25 times. CP or DZ with fosthiazate reduced the time for fosthiazate to penetrate the RKN cuticle compared to fosthiazate alone. CP or DZ combined with low or medium rate of fosthiazate increased the total cucumber yield, compared to the use of each product alone. A low-dose fosthiazate with DZ improved total yield more than a low dose fosthiazate with CP. Extending the half-life of fosthiazate and reducing the time for fosthiazate or fumigant to penetrate the RKN cuticle were the two features that gave the fumigant-fosthiazate combination its synergistic advantage over these products used singularly. This synergy provides the opportunity for farmers to use a low dose of fosthiazate which lowers the risk of RKN resistance. Farmers could combine DZ at 30 g m~(-2) with fosthiazate at a low rate of 0.375 g m~(-2) to control RKN and adequately control two major soil-borne diseases in cucumber greenhouses.     

Overexpression of G10-EPSPS in soybean provides high glyphosate tolerance

Glyphosate is a highly efficient, broad-spectrum nonspecific herbicide that inhibits the 5-enolpyruvylshikimate-3-phosphate synthase(EPSPS)-mediated pathway of shikimic acid. The screening of glyphosate-resistant EPSPS gene is a major means for the development of new genetically modified glyphosate-resistant transgenic crop. Currently, the main commercialized glyphosate-resistant soybean contains glyphosate-resistant gene CP4-EPSPS. In this study, a G10-EPSPS gene was reported providing glyphosate resistance in Zhongdou 32. Here, G10-EPSPS gene was introduced into soybeans through Agrobacterium-mediated soybean cotyledon node. PCR, Southern blotting, semi-quantitative RT-PCR, qRT-PCR, and Western blotting were used, and the results revealed that G10-EPSPS had been integrated into the soybean genome and could be expressed steadily at both mRNA and protein levels. In addition, glyphosate resistance analysis showed that the growth of transgenic soybean had not been affected by concentrations of 900 and 2 700 g a.e. ha~(–1) of glyphosate. All the results indicated that G10-EPSPS could provide high glyphosate resistance in soybeans and be applied in production of glyphosate-resistant soybean.